And one by one as she filled the little flasks of chained death, the engineer stoppered them with his left hand.

When the last was done, Stern drew a tremendous sigh, and dashed the sweat from his forehead with a gesture of victory.

Into the residue in the dish he poured a little nitric acid.

That's got no kick left in it, now, anyhow,” said he relieved. “The HNO3 tames it, quick enough. But the bottles--take care--don't tip one over, as you love your life!”

He stood up, slowly, and for a moment remained there, his face in the shadow of the lamp-shade, holding to the table-edge for support, with his left hand.

At him the girl looked.

“And now,” she began, “now--?”

The question had no time for completion. For even as she spoke, a swift little something flicked through the window, behind them.

It struck the opposite wall with a sharp crack! then fell slithering to the floor.

Outside, against the building, they heard another and another little shock; and all at once a second missile darted through the air.